The University of Graz (German, Karl-Franzens-Universität Graz), a highly respected university located in Graz, Austria, is the second-largest and second-oldest university in Austria. Karl-Franzens-Universität, also referred to as the University of Graz, is the city's oldest university, founded in 1585 by Archduke Charles II of Austria. For most of its existence it was controlled by the Catholic Church, and was closed in 1782 by Emperor Joseph II in an attempt to gain state control over educational institutions. Joseph II transformed it into a lyceum where civil servants and medical personnel were trained. In 1827 it was re-instituted as a university by Emperor Francis I, thus gaining the name Karl-Franzens-Universität, meaning Charles Francis University. Over 22,000 students are currently enrolled at this university. Ludwig Boltzmann was professor at the Karl-Franzens Universität twice (1869-1873 and 1876-1890) developing his statistical theory of heat. Nobel Laureate Otto Loewi taught at the University of Graz from 1909 until 1938. Victor Franz Hess (Nobel prize 1936) graduated in Graz and taught here (1920-1931, 1937-1938).